@@ -14,10 +14,12 @@
  * file.
  */
 
 #import "OFObject.h"
 
+OF_ASSUME_NONNULL_BEGIN
+
 /*!
  * @protocol OFHash OFHash.h ObjFW/OFHash.h
  *
  * @brief A protocol for classes providing hash functions.
  */
@@ -80,5 +82,7 @@
  *	    you are still interested in the previous digest, you need to memcpy
  *	    it yourself before calling @ref reset!
  */
 - (void)reset;
 @end
+
+OF_ASSUME_NONNULL_END